Sixteen experiments are proposed to examine the on-line processing of sentences by child and adult speakers of English, German, Hungarian, and Italian. The experiments focus on the processing of devies involved with role identification and anaphoric reference, seeking to test the resilience of a plurifunctional parallel-activation model of sentence processing called the Competition Model. This model is presented as a performance model, not a competence model. As a model of adult procesing, it seeks to acount for performance in terms of relative cue weight. Cue weight, in turn, is predicted to be a function of the objective validity of cues in the linguistic environment. Development is viewed as a process of acquiring a system of cue weights that correctly reflects various aspects of cue validity. The specific studies being proposed fall into five classes: 1. the collection of corpora of adult-adult and adult-child discourse in the four languages and the analysis of these corpora in order to compute cue validity values, 2. the examination of the on-line assignment of the subject role using auditory presentation of digitized speech with pictorial probes; 3. monitoring for the occurrence of errors in gender agreement, subject-verb agreement, word order, and case-marking; 4. monitoring for the occurrence of words whose shape is predicted by various morphosyntactic devices; and 5. recognition of a pictorial probe during the process of real time integration of anaphoric reference. These studies are the first extensive investigation of on-line sentence processing in children and the first application of on-line techniques to cross-linguistic research.